Tenth Planet?
SCIENTISTS have found a new world
orbiting the solar system – more than 3 billion kilometres further
away from the Sun than Pluto and 40 years away from Earth in a space
shuttle.
NASA is expected to announce today the discovery of the space
object, which some experts believe could be a new planet.
It is provisionally known as Sedna, after the Inuit goddess of the
sea.
The discovery of Sedna – 10 billion kilometres from Earth – is a
testament to the new generation of high-powered telescopes.
Measurements suggest Sedna's diameter is almost 2000km – the biggest
find in the solar system since Pluto was discovered 74 years ago. It
is believed to be made of ice and rock, and is slightly smaller than
Pluto.
The find will reignite the debate over what constitutes a planet.
Some scientists claim even Pluto is too small to count as one.
According to astronomer Michael Brown of the California Institute of
Technology, who discovered Sedna, there could be many other new
worlds orbiting the Sun and waiting to be discovered.
"Sedna is very big, and much further out than previous discoveries,"
he said. "I'm pretty sure there are other large bodies up there
too."
But physicist and cosmologist Paul Davies, of Sydney's Macquarie
University, said it was folly to describe Sedna as a planet. "It's
fun, it's exciting, but let's keep it in proportion," Professor
Davies said yesterday.
He said scientists had known for "a decade or so the solar system
does not come to an abrupt halt" and there were a number of "planetessimals"
or little planets, like Sedna.